1. Field of the Invention
The present invention relates to a fixing device that is provided in a wet electrophotographic image forming device.
2. Description of the Related Art
In recent years, as an on-demand printing device or the like in which high quality and high resolution are required in commercial printing or the like, a wet electrophotographic method in which the particle diameter of toner is low and high-speed printing can be performed has been utilized. In the wet electrophotographic method, a wet developer (liquid developer) in which toner is dispersed in a carrier liquid is used, a toner image is transferred to a sheet and thereafter the toner image is fixed to the sheet with a fixing roller and the like.
The carrier liquid in a toner layer of the toner image acts so as to inhibit the production of internal cohesion of the toner layer. Hence, when the amount of carrier liquid in the toner layer is excessively large, an adhesive force between the toner and the fixing roller (pressurizing and heating unit) becomes greater than the internal cohesion of the toner layer or an adhesive force to the sheet, with the result that a so-called offset occurs in which the toner is moved to the fixing roller.
It can be considered that in order to cope with the offset described above, a non-contact heating portion is provided on the upstream side with respect to the fixing roller. The toner is melted in the non-contact heating portion, and thus the carrier liquid in the toner is pushed out to penetrate into the sheet, with the result that it is possible to reduce the amount of carrier liquid in the toner layer.
However, even when the carrier liquid is pushed out from the toner layer, if the toner image enters the fixing roller before the penetration of the carrier liquid becomes sufficient, the offset may be insufficiently reduced. In view of the foregoing problem, the present invention has an object to provide a fixing device in which the penetration of the carrier liquid is appropriately performed and with which it is possible to sufficiently reduce the offset.